Smoking-related emphysema is a chronic inflammatory disease driven by the T sub(H)17 subset of helper T cells through molecular mechanisms that remain obscure. Here we explored the role of the ...microRNA miR-22 in emphysema. We found that miR-22 was upregulated in lung myeloid dendritic cells (mDCs) of smokers with emphysema and antigen-presenting cells (APCs) of mice exposed to smoke or nanoparticulate carbon black (nCB) through a mechanism that involved the transcription factor NF- Kappa B. Mice deficient in miR-22, but not wild-type mice, showed attenuated T sub(H)17 responses and failed to develop emphysema after exposure to smoke or nCB. We further found that miR-22 controlled the activation of APCs and T sub(H)17 responses through the activation of AP-1 transcription factor complexes and the histone deacetylase HDAC4. Thus, miR-22 is a critical regulator of both emphysema and T sub(H)17 responses.
Smoking-related emphysema is a chronic inflammatory disease driven by T helper 17 (T
H
17) cells through molecular mechanisms that remain obscure. Here we have explored the role of microRNA-22 ...(miR-22) in emphysema. MiR-22 was upregulated in lung myeloid dendritic cells (mDCs) of smokers with emphysema and antigen-presenting cells (APCs) of mice exposed to smoke or nanoparticulate carbon black (nCB) through a mechanism involving NF-κB. MiR-22-deficient mice, but not wild-type, showed attenuated T
H
17 responses and failed to develop emphysema after exposure to either smoke or nCB. We further show that miR-22 controls APC activation and T
H
17 responses through activation of AP-1 transcription factor complexes and histone deacetylase (HDAC) 4. Thus, miR-22 is a critical regulator of both emphysema and T
H
17 responses.
Caspases are widely conserved proteases considered to be essential effectors of apoptosis. We identified a novel Drosophila gene, dredd, which shares extensive homology to all members of the caspase ...gene family. Cells specified for programmed death in development exhibit a striking accumulation of dredd RNA that requires signaling by the death activators REAPER, GRIM, and HID. Furthermore, directed misexpression of each activator was sufficient to drive ectopic accumulation of dredd RNA. Heterozygosity at the dredd locus suppressed apoptosis in transgenic models of reaper- and grim-induced cell killing, demonstrating that levels of dredd product can modulate signaling triggered by these death activators. Finally, expression of REAPER, GRIM, and HID was found to trigger processing of DREDD protein precursor through a mechanism that is insensitive to, and upstream of, known caspase inhibitors. Taken together, these observations establish mechanistic connections between activators of apoptosis and a new downstream death effector in Drosophila.
In mammals and Drosophila, apoptotic caspases are under positive control via the CED‐4/Apaf‐1/Dark adaptors and negative control via IAPs (inhibitor of apoptosis proteins). However, the in vivo ...genetic relationship between these opposing regulators is not known. In this study, we demonstrate that a dark mutation reverses catastrophic defects seen in Diap1 mutants and rescues cells specified for Diap1‐regulated cell death in development and in response to genotoxic stress. We also find that dark function is required for hyperactivation of caspases which occurs in the absence of Diap1. Since the action of dark is epistatic to that of Diap1, these findings demonstrate that caspase‐dependent cell death requires concurrent positive input through Apaf‐1‐like proteins together with disruption of IAP–caspase complexes.
Caspases are widely conserved proteases considered to be essential effectors of apoptosis. We identified a novelDrosophilagene,dredd,which shares extensive homology to all members of the caspase gene ...family. Cells specified for programmed death in development exhibit a striking accumulation ofdreddRNA that requires signaling by the death activators REAPER, GRIM, and HID. Furthermore, directed misexpression of each activator was sufficient to drive ectopic accumulation ofdreddRNA. Heterozygosity at thedreddlocus suppressed apoptosis in transgenic models ofreaper- andgrim-induced cell killing, demonstrating that levels ofdreddproduct can modulate signaling triggered by these death activators. Finally, expression of REAPER, GRIM, and HID was found to trigger processing of DREDD protein precursor through a mechanism that is insensitive to, and upstream of, known caspase inhibitors. Taken together, these observations establish mechanistic connections between activators of apoptosis and a new downstream death effector inDrosophila.
Mammals and insects employ similar Rel/NF‐κB signaling cascades in their humoral immune responses. The mammalian interleukin‐1 type I receptor (IL‐1R) is one way of activating this cascade. The ...Drosophila Toll protein, whose cytoplasmic domain shows striking similarity to that of the IL‐1R, acts in the humoral antimicrobial response. Here we demonstrate that a second IL‐1R‐related Drosophila protein, 18‐Wheeler (18W), is a critical component of the humoral immune response. 18‐wheeler is expressed in the larval fat body, the primary organ of antimicrobial peptide synthesis. In the absence of the 18W receptor, larvae are more susceptible to bacterial infection. Nuclear translocation of the Rel protein Dorsal‐like immunity factor (Dif) is inhibited, though nuclear translocation of another Rel protein, Dorsal, is unaffected. Induction of several antibacterial genes is reduced following infection, relative to wild‐type: attacin is reduced by 95%, cecropin by 65% and diptericin by 12%. Finally, 18‐wheeler (18w) expression is induced in response to infection and, in addition to the receptor form, four immune‐specific transcripts and proteins are produced.
Programmed cell death (PCD) is a highly conserved process that occurs during development and in response to adverse conditions. In Drosophila, most PCDs require the genes within the H99 deficiency, ...the adaptor molecule Ark, and caspases. Here we investigate 10 cell death genes for their potential roles in two distinct types of PCD that occur in oogenesis: developmental nurse cell PCD and starvation‐induced PCD. Most of the genes investigated were found to have little effect on late stage developmental PCD in oogenesis, although ark mutants showed a partial inhibition. Midstage starvation‐induced germline PCD was found to be independent of the upstream activators and ark although it requires caspases, suggesting an apoptosome‐independent mechanism of caspase activation in mid‐oogenesis. These results indicate that novel pathways must control PCD in the ovary. genesis 45:396–404, 2007. Published 2007 Wiley‐Liss, Inc.
Proteins are biological macromolecules responsible for the majority of all physiological processes. In order to properly function proteins are required to adopt highly ordered structures. These ...structural aspects may be found within a single protein or arise from multi-protein complexes. Here hydrogen/deuterium exchange mass spectrometry (HDX-MS) is employed as a tool to determine the extent of protein higher order structure. Exposure to D2O-based solvent causes the heavier isotope to exchange with amide hydrogens in the polypeptide backbone. This exchange is mainly dependent on protein conformation because the presence of stable hydrogen-bonded secondary structure will impede the incorporation of deuterium when compared to regions that are unstructured. In this work HDX-MS is used to study denaturant-induced unfolding of oxidized and reduced cytochrome c as well as ATP binding to the ε subunit of FOF1-ATP synthase. This work also lays the foundation to use this technique to study larger, more complex systems.
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